Stereoscopic eyewear with stray light management

ABSTRACT

Disclosed embodiments relate to eyewear configured to reduce stray light. An exemplary embodiment of the eyewear accounts for various design factors, including the cross sectional profile of the rim, the micro topography of the rim surface, the reflectivity, the theatre or room geometry, proximity of the eye to the lens, lens size, and the screen gain. An exemplary eyewear includes lenses connected to the rim sections of a frame, and a path may be defined through a maximum height of the outer flange portion of a rim section and a maximum height of the inner flange portion of the rim section. The path may be inclined at an angle relative to an angle α relative to a longitudinal axis defined by the lenses.

CROSS-REFERENCE TO RELATED APPLICATION

This application relates and claims priority to commonly-assigned U.S.Provisional Patent Application No. 61/446,385, filed Feb. 24, 2011, andentitled “Stereoscopic eyewear with stray light management,” which isincorporated herein by reference for all purposes.

TECHNICAL FIELD

This disclosure generally relates to addressing eyewear and morespecifically relates to stereoscopic eyewear configured to reduce straylight from reaching the eye.

BACKGROUND

Stereoscopic systems operate by presenting two distinct images to aviewer. Filtering may be utilized to present one image to one eye andthe second image to the other eye. Filtering may employ polarization orspectral-division methods to separate the two images. Spectacles (oreyewear) pass orthogonal polarization states to each eye and completethe filtering function.

SUMMARY

An embodiment of eyewear configured to reduce stray light comprises aframe having rim sections and lenses connected to the rim sections ofthe frame, each lens comprising a field of view (FOV) having a halfangle θ₀. Each rim section may comprise an outer portion and an innerportion, and a path may be defined through a maximum height of the outerportion and a maximum height of the inner portion, the path beinginclined at an angle α relative to a longitudinal axis defined by thelenses.

Another embodiment of eyewear configured to reduce stray light comprisesa frame having rim sections and lenses connected to the rim sections ofthe frame, each lens comprising a field of view (FOV) having a halfangle θ₀. Each rim section may comprise an outer flange portion and aninner flange portion, the outer and inner flange portions defining achannel therebetween. A portion of the each lens may be disposed in thechannel of a respective rim section. A path may be defined through amaximum height of the outer flange portion and a maximum height of theinner flange portion, the path being inclined at an angle α relative toa longitudinal axis defined by the lenses. The maximum height of theouter flange portion may be greater than the maximum height of the innerflange portion and comprises a sloped profile from an outer edge to aninner edge of the outer flange, and the angle α may be greater than asteepest incidence angle associated with a screen.

Related methods for designing and manufacturing the eyewear of thepresent disclosure are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a geometric model of a first exemplary embodiment ofeyewear configured to reduce stray light, in accordance with the presentdisclosure;

FIG. 2 illustrates specular reflections in the first exemplaryembodiment of the eyewear shown in FIG. 1, in accordance with thepresent disclosure;

FIG. 3 illustrates a geometric model of a second exemplary embodiment ofeyewear configured to reduce stray light, in accordance with the presentdisclosure;

FIG. 4 illustrates a geometric model of a third exemplary embodiment ofeyewear configured to reduce stray light, in accordance with the presentdisclosure;

FIG. 5A illustrates an exemplary embodiment of eyewear having reducedstray light, in accordance with the present disclosure;

FIG. 5B illustrates another exemplary embodiment of eyewear havingreduced stray light, in accordance with the present disclosure;

FIG. 6 illustrates another exemplary embodiment of eyewear havingreduced stray light, in accordance with the present disclosure; and

FIG. 7 illustrates an exemplary lens designed to reduce stray light, inaccordance with the present disclosure.

DETAILED DESCRIPTION

When designing passive and active (shutter-glass) eyewear forstereoscopic 3D displays, an objective may be to provide the viewer anexperience that is as close as possible to being eyewear-free. As such,any persistent reminder that the imagery is being viewed through eyewearshould be eliminated wherever possible through design considerations.This includes minimizing bulkiness/weight, and designing the frame tomaximize comfort. In some case, material cost may be a constraint.According to the present disclosure, optical performance may also be adesign consideration. The present disclosure includes embodiments thatconsider the eyewear as an optic, which through several stray lightgenerating mechanisms, may limit the quality of the experience.

According to the present disclosure, the design of the lens and framemay be such that the eye is comfortably focused in the plane of theimage (typically the far-field), which is best accomplished under thefollowing circumstances:

1. The lens is large enough, and in close enough proximity to the eyethat the eyewear field of view (FOV) is substantially larger than theangular extent of the imagery;

2. The lens induces an imperceptible level of optical distortion; and

3. The stray light associated with every aspect of the eyewear isminimized.

In stereoscopic 3D cinema, the functional purpose of the eyewear is todecode the (stereo pair) imagery encoded at the projector. Theeffectiveness of this lock-and-key arrangement is typically measured atthe system-level by extracting the relative leakage of the unintendedimage, given as a contrast ratio, or cross-talk. This test is typicallymade through the analyzer (eyewear lens material) using a photopicallyweighted detector. It is a point measurement, made with a narrowacceptance angle, typically along the path yielding the best-casecontrast. Another measurement made by manufacturers of such equipment isto characterize the contribution of any encoding mechanism to loss inANSI (checkerboard) contrast, which is typically done directly in frontof the screen without eyewear. Neither of these tests captures loss inimage quality due to any unintended characteristics of the eyewear, asexperienced by an actual observer. This degradation is highly dependentupon optical design considerations of the eyewear, or lack thereof,ultimately determined by the degree of stray light control.

Stray light is taken to be any component of light that does not followthe intended path from the image generation device to the viewer. It canbe the result of direct scatter from, for example, lens materials andadhesives (which may be associated with forward scatter, or haze),primary (surface/bulk) scatter from a frame element, or secondaryscattering, as from skin/eye and subsequent frame elements. The presentdisclosure provides embodiments of 3D eyewear designs that may reduce orsubstantially eliminate such scatter, thereby enhancing the overall“see-through” and quality of the 3D experience.

As evidenced by prevalent 3D cinema eyewear designs (for example, byRealD, IMAX, Dolby, and Master Image), little attention is given to theframe as an optic that has important performance implications. Asdiscussed above, performance measurements are made under highlycontrolled conditions along the intended optical path through the opticstrain. In reality, portions of the frame frequently act as secondaryemission sources, directing stray light into the eye and compromisingthe overall visual experience. It should be noted that while stray lightequally affects the quality of 2D content, specific relevance to 3Dincludes the fact that decoding eyewear is currently a necessity innon-autostereoscopic systems. The background light contributed by theeyewear is more relevant to loss in ANSI (checkerboard) contrast, versusghost images associated with cross-talk.

According to an embodiment of the present disclosure, the eyewear framemay be configured to reduce or substantially eliminate reflection andscatter from entering the eye. In particular, light reflecting from theinterior of the rim is often within the field of view (FOV) of the eye.The cross sectional profile of the rim, the micro topography of the rimsurface, the reflectivity which may depend upon ray direction, thetheatre geometry, the proximity of the eye to the lens, the lens size,and the screen gain which may determine the relative strength of inputrays versus angle, all play a role in determining the amount of lightcollected by the eye from the frame.

According to the present disclosure, the frame geometry may be designedto minimize the amplitude of primary scatter collected by the eye. Thiscan be done by analyzing the theatre geometry, or viewing locus, whichis derived by superimposing the field of observation for a range ofaudience viewing locations and extracting the perimeter. Thisoptimization may exclude certain viewers, including, for example,extreme viewing locations in very short-throw ratios auditoriums, in theevent that it creates tradeoffs in the optimization. In an exemplaryembodiment, however, an optimized frame can satisfy the requirements foroptimum viewing over the entire cinema ensemble.

A second-order consideration is the strength of scatter from aparticular screen location, which can be highly dependent upon thesystem geometry. A more detailed analysis incorporates a weightingfunction associated with various angle dependent elements. Factors thatcontribute to diminishing efficiency as a function of angle include theprojector, the screen, and the 3D shuttering mechanism (e.g. forsequential polarization systems). The latter may be either a mechanicalor LC based polarization switch with suitable analyzing eyewear, orshutter glasses worn directly over the eye.

An objectionable aspect of many current polarization-based 3D theatresystems is that the image brightness may diminish rapidly from thescreen center to the screen corners. A DLP projector may show a 10-20%fall-off in image brightness. A polarization preserving screen may showmore than an 80% drop in gain in the corners, and a liquid crystal (LC)based polarization switch may show a 20-30% drop in brightness, asobserved through the analyzing eyewear. As these limitations are removed(see co-pending, commonly-owned patents and applications, including U.S.Pat. No. 7,898,734, and U.S. patent application Ser. Nos. 12/977,026,12,976,986, and 13/182,381, all of which are hereby incorporated byreference in their entirety), image brightness can increase several foldat the extreme viewing angles, greatly improving the image quality, butpotentially exacerbating the stray light contribution from eyewearscattering events. This occurrence in the industry will increase theneed for the inventive eyewear, which precisely manages light incidenton the eyewear from extreme angles.

Typically, eyewear frames may be made using an injection moldingprocess, with molds manufactured using conventional (CNC) machining, orelectronic discharge machining (EDM). The micro-topography of the moldsurface may depend both upon the intrinsic characteristics of theprocess, as well as any subsequent steps to modify the surface. Forinstance, random texture can be added by attacking the surfacechemically, or mechanically, using various methods. Conversely,polishing steps can be incorporated to improve the smoothness of thesurface. The frames may be manufactured by injecting a molten polymerinto a mold cavity, followed by a cooling step, and releasing the partfrom the mold. Conventional polymers used for eyewear frames may includeAcrylonitrile butadiene styrene (ABS), Polycarbonate (PC), and otherpolymers and co-polymers. The resulting frame is substantially conformalto the mold even at optical scales, so the micro-topography of the moldcan determine the surface finish.

An eyewear frame that is uniform on an optical scale tends to producestray light that is highly directional when it is illuminated. Like anyspecular reflection, the direction of the outgoing ray is determined bythe input direction and the local surface normal. Such an interactionobeys Fresnel's equations for reflection at the air/polymer interface.To the extent that at least portions of the frame surface direct raysscattered from a location of the viewing screen into the field of view,the quality of the 3D experience may be compromised by the associatedstray light. Among other things, the distribution of light within thevisual FOV is highly dependent upon the specific geometry of the eyewearrim. For instance, a rim may have a flat facet portion that steersincident light from an illumination direction into the FOV. One suchexample is a goggle-like pair of IMAX cinema eyewear, which has a flatrim (substantially normal to the lens material), with a total depth ofapproximately 10 mm. Light reflected from such a large rim can createthe perception that the imagery is being viewed through a ringilluminator. Furthermore, the intensity of this stray light is highlydependent upon image content. Specifically, light specularly reflectedfrom a rim facet that is captured by the eye can originate from a smallregion (likely near the edge) of the cinema screen. In such a case, thestray light may create the additional distraction that it is temporallymodulated.

As an alternative to a faceted rim, a rim may have a more roundedcontour that can locally approximate a cylindrical reflector. Such asurface will spread an incident ray in one dimension over a range ofangles dictated by the radius of curvature. While this suppresses thecontribution from a single direction, as in the former case, in thisinstance the eye can capture light from a larger area of the emittingsurface. That is, the distribution of scatter into a broader range ofangles increases the probability that the eye will capture light from agreater area of the rim surface.

A more extreme situation may exist when the frame topography maps aninput ray to a random distribution of outgoing rays. Again, thedistribution further depends upon the frame contours, or surface-normaldistribution. Surfaces with random or deterministic textures have thetendency to scatter light into a broader distribution of angle space, asis frequently characterized by the bi-directional reflectancedistribution function (BRDF). The BRDF is the differential reflectivityof the surface per solid angle. Highly textured surfaces, such as thoseaccurately approximated as a Lambertian scatterer, have the benefit ofdispersing the stray light broadly in angle space and eliminating the“hot spot”, though the ability to control stray light from suchstatistical surfaces is more challenging.

In certain instances, frames are manufactured with a matte finish, forappearance and (perhaps erroneously) for functional purposes.Functionally, a matte surface disperses the specular component ofreflection, and depending upon the specific texture, can potentiallyhave a lower total integrated scatter (TIS) than a smooth surfacecomposed of the same material. The TIS is defined as the ratio of totalpower propagating away from the scattering surface, to that incidentupon it. Some reduction in TIS can be achieved through multiple lossyscattering events. However, because average reflectivity can increasewith incidence angle, the slope probability statistics of the surfaceare an important factor. Matte surfaces are typically Gaussian randomnoise based, with aspect ratio (mean in-plane feature size to meanheight) having significant influence on the probability of multiplescattering events. Textured surfaces that significantly reduce TIS aredesirable, but it is difficult to suppress stray light to animperceptible level. Nevertheless, engineered surfaces that manipulatethe BRDF, such that scatter from the frame surface is not directed tothe eye from a representative range of illumination directions, areconsidered embodiments of the present disclosure.

The reflection efficiency of a ray incident on an optically smoothsurface depends upon the refractive index of the polymer, the incidenceangle, and the state of polarization (SOP), in accordance with Fresnel'sequations for reflection. The direction of the reflected ray dependsupon the input ray direction and the local surface normal, defining thelocal specular direction. If the surface is rough, the situation is morecomplex. Here, the distribution of scatter about the specular directionalso depends upon the incidence angle and the surface topography, whichis captured by the BRDF. What has not been considered thus far is therelatively strong component transmitted into the bulk polymer medium.

For a typical polymer at a moderate incidence angle, the transmission ofunpolarized light into the bulk can exceed 90%. As such, it is highlydesirable that the frame design carefully manages the transmittedcomponent. The degree to which light transmitted into the polymerscatters into the observation direction depends upon the detailedmolecular structure of the medium, which can produce refractivein-homogeneity, as well as the interaction length with the bulk. Bulkscatter, and the wavelength dependence with which light propagates intothe polymer medium, determines the color and brightness of the framematerial. Frequently, 3D eyewear frames utilize polymers that eitherhave low intrinsic visible transmission or that contain additives, suchas black dyes or carbon black. This has the desired effect of minimizingthe interaction length of light in the medium at all visiblewavelengths, thus attenuating this particular contribution to straylight. While there may be no specific concern that bulk scatter from theframe contributes to observed stray light, a desirable approach is tominimize it. Since the angular distribution of bulk scatter in manypolymers tends to be broad, strong absorbers can virtually eliminate thetransmitted component before it can scatter significant power. However,while this makes a compelling case for utilizing low transmissionmaterials for 3D eyewear, there may be instances where an alternativesolution is desired.

The present disclosure also includes light control frame designs that donot require high visible absorption (black) frame material. For example,a frame material can even be fabricated of a transparent polymer,provided that light transmitted into the polymer material is notre-directed to the eye via one or more scatter events. This can bechallenging, even in the cinema environment, when considering lightincident on the rim portion of the frame. Here, a thin absorbingcoating, or a second opaque piece may be utilized to aperture the lensand eliminate stray light in this specific portion of the frame.Alternatively, as an example, an opaque mask can be coated/depositeddirectly onto the lens material prior to die-cutting the lens from thesheet stock.

Also according to the present disclosure, frame designs are providedthat minimize the contribution of the surface scatter component of straylight, thus maximizing the lens “see-through” and contrast of the 3Dexperience. Optimum frame designs are tailored to the specific useenvironment. In particular, optimized frame designs take intoconsideration the direction with which light is incident upon the framefrom various light sources. Such environments may include a cinemaauditorium, a museum, a theme-park ride, a home theatre, a living room(which may contain background illumination sources from multiplelocations), a computer gaming environment, or an industrial setting.

A cinema environment is one in which ambient lighting is relativelycontrolled. It is reasonable to assume in this type of environment thatthe front projection screen is the dominant source for generatingprimary, and even secondary stray light components of significantamplitude. A primary scattering event is one that connects a location ofthe screen (or image source) to the eye via a single interaction with aframe surface element.

A secondary scattering event is one that connects a location of thescreen to the eye via two scattering events, including (e.g.) areflection from the viewer's face (and eye) to the interior surface ofthe lens or frame. In this particular case, the reflection from the facecontains both surface and bulk scatter elements, while the second eventis the combined specular reflection of this light from the front andback surfaces of the lens element. While there is little that can bepractically done to attenuate the reflection from skin and eyes, thereflection from the lens can be reduced by using anti-reflection (AR)coatings.

In a linear polarization based system, using typical hard-coatedtriacetate (TAC) polarizer (and assuming that the light scattered fromskin is substantially unpolarized), the reflection from the innersurface of the polarizer is approximately 4%, while that from the outersurface is approximately halved due to the action of the linearpolarizer. This gives a combined reflection from the lens ofapproximately 6%, wherein roughly 6% of light scattered from theskin/eyes in the first pass is returned by the lens to the viewer. Inorder to eliminate this reflection, it is desirable to apply AR coatingsto both the interior and exterior of the lens.

In a circular polarizer based system, the reflection from the innersurface of the polarizer is again approximately 4%. There is negligiblereflection at the polarizer/QW (quarter-wave retarder) interface. Asbefore, the polarizer halves the transmitted power, with 4-5% of theremaining light reflected at the exterior (PC) QW/Air interface.However, note that the round-trip of the QW converts the linearpolarization to the orthogonal polarization, with this componentsubsequently absorbed by the analyzer. According to an embodiment of thepresent disclosure, AR coatings may only be applied to the interiorsurface of the lens to eliminate the secondary reflection term, whilemaintaining low cost. Further cost reduction can be achieved by applyingAR coatings to an inexpensive Polyethylene terephthalate (PET) substrateusing a roll-to-roll process. This substrate may be laminated usingPressure Sensitive Adhesive (PSA) to the linear polarizer, and can evenpotentially replace a TAC protective film on the linear polarizer. Thisassumes that issues, such as differences in mechanical properties of thesubstrates, are not an issue (e.g. issues causing curl). Because thepolarization is already analyzed, the anisotropy of the PET substrate isnot an issue.

AR coatings are a viable option for reducing the effects of secondaryreflection on polarization based 3D eyewear. However, to the extent thatthe lens requires high reflectivity (e.g. dichroic-filter based spectraldivision stereo systems offered by Dolby), this is not the case. Sincegreater than half of the visible spectrum is reflected by each lens insuch systems, secondary reflections are extremely strong. A compellingdemonstration is as follows: observe a bright (point) light source in adark room through Dolby glasses. When focusing in the near field, a verystrong image of the viewer's eye/face, due to secondary reflection, isclearly observable that is fundamentally coupled to the image source. Inpractice, where the viewer is focused in the far-field, this lightrepresents a distracting background source that detracts from the 3Dexperience. This is an intrinsic limitation of such systems when usingreflecting filters.

According to an exemplary embodiment, an optimized frame of the presentdisclosure is one that has near zero primary reflection, or at least ata negligible level (<1 part in 1,000), for all viewing locations. Thismay be accomplished by engineering the frame local surface normal, suchthat there is no path connecting a screen location to the eye through asingle surface scatter (or specular reflection) event. In view of thevarious design considerations discussed above, exemplary embodiments foreyewear with reduced stray light will be discussed below with respect toFIGS. 1-7.

FIG. 1 is a schematic diagram illustrating a one-dimensional analysis ofthe geometry of a single-facet (optically smooth) model for the eyewearframe. In the illustrated embodiment, the theatre geometry is such thatlight is incident on the lens 102 from the screen (not shown) over arange of angles encompassing the lens normal 104, to an extreme screenperimeter angle of θs. Assume a simple model for the eyewear, where thehalf-angle θo for the FOV of the lens is given by

θ o = tan⁻¹[r/d]where r is the lens radius 106, and d is the distance 108 from the eye110 to the lens 102.

FIG. 2 is a schematic diagram of the frame 100 shown in FIG. 1 andprovides an illustration of the out-going specular reflection rays 112from the rim 120 towards the eye 110. Some of the specular reflectionrays 112 are within the FOV while others may be outside of the FOV.Referring back to FIG. 1, in the event that a critical incidence angleθc≦θs exists, there is a corresponding specular reflection of the rim120 within the FOV. Depending on the orientation of the facet 122 of therim 120, different amount of specular reflection may be achieved. In afirst case, if the facet normal is parallel to the lens 102 as shown inFIGS. 1 and 2, the critical angle θc is exactly the lens FOV, or θc=θo.So if θs>θo, there is a specular reflection of the rim 120.

FIG. 3 is a schematic diagram showing a rim 200 having a facet 202tipped outwardly by angle α<0. Using the same model considered in FIG. 1except replacing the rim 120 with the rim 200, the critical angle θc isreduced to θo−2|α|, which further increases the probability that thespecular reflection angle is within the capture angle of the screen. Ifthe facet 202 is further tipped outward until |α|>θo, the inner portion204 of the rim 200 blocks the incident light, and there exists nospecular reflection from the facet 202 to the eye 206 for any incidenceangle. The embodiment of FIG. 3 is a desirable embodiment if |α|>θo.

FIG. 4 is a schematic diagram showing a rim 300 having a facet 302tipped inwardly by angle α>0. Using the same model considered in FIG. 1except replacing the rim 120 with the rim 300, the critical angle θc isincreased to θo+2|α|, which reduces the probability that the specularreflection angle is within the capture angle of the screen. In a numberof embodiments, a modest inward tip is sufficient to insure that nospecular reflection is within the capture angle of the screen. As thefacet 302 is further tipped inward, such that α≧θs, there ceases to beany reflection from the facet 302, as it is completely shadowed by theouter portion 304 of the rim 300. As such, the embodiment of FIG. 4 is adesirable embodiment.

The above is a simple illustration of how the rim geometry can affectthe light stray light at the eye. An embodiment of the presentdisclosure is illustrated in FIG. 5A. FIG. 5A shows a cross-section of aframe 400 comprising rim 402, and the attachment of a lens 404 to therim 402. In the illustrated embodiment, the lens 404 is clamped betweeninner and outer portions 406, 408 of the rim 402. In one embodiment, theouter portion 408 has a flange portion 410 that holds the lens 404.Similarly, the inner portion 406 has a flange portion 412 that holds thelens 404. In an exemplary embodiment, the inner and out portions 406,408 may be modularly attached and may form a channel 414 that holds thelens 404 in place. A path may be defined through a maximum height 416 ofthe outer portion 408 and a maximum height 418 of the inner portion 406such that the path is inclined at an angle α relative to a longitudinalaxis 420 defined by the lenses. In the illustrated embodiment, themaximum height 416 of the outer portion 408 is greater than the maximumheight 418 of the inner portion 406. This configuration corresponds tothe inward tipping model shown in FIG. 4. In such an embodiment, theangle α may be greater than a steepest incidence angle θs associatedwith a screen. To avoid a facet that can steer light to the eye, theouter portion 408 may have a sloped or curved profile from an outer edge430 to an inner edge 432 of the outer portion 408 as shown in FIG. 5A.

Another exemplary embodiment is illustrated in FIG. 5B. FIG. 5B shows across-section of a frame 400 comprising rim 402, and the attachment of alens 404 to the rim 402. In the illustrated embodiment, the lens 404 isclamped between inner and outer portions 406, 408 of the rim 402. Themaximum height 416 of the outer portion 408 may be smaller than themaximum height 418 of the inner portion 406, which would correspond tothe outward tipping model shown in FIG. 3. In such an embodiment, theangle α may be greater than the half angle θ₀ of the FOV (not shown). Toavoid a facet that can steer light to the eye, the inner portion 406 mayhave a sloped or curved profile from an outer edge to an inner edge ofthe outer portion, similar to the sloped profile of the outer portion408 in FIG. 5A.

Another potential source of stray light is the front of the temple pieceand the attachment point (or hinge) between the frame pieces. This canalso be within the peripheral FOV, having a relatively large surfacearea, and thus can contribute significant stray light. As with the rimportion, while there may be no specular path from screen to the eye, dueto relatively large angles involved, there can be a significantcontribution from surface texture and bulk scatter.

There are numerous examples of 3D cinema frame designs of the prior artthat incorporate large surface area temples and deep rim panels,presumably to help manage stray light. The approach seems to be thatenclosing the volume containing the eye is needed to reduce the ambientlevel. While light can reach the viewer from extreme angles via scatterfrom the auditorium walls and ceiling and adjacent viewers, it is arelatively weak contributor to stray light. In a cinema environment, thedominant source of stray light follows the path directly from screen toviewer. As such, large surface side panels actually have the oppositeeffect of increasing stray light via scatter from the interior.Moreover, designs often incorporate matte finishes for such surfaces.Given that this surface is in the periphery (i.e. outside of thespecular collection angle), this only increases the probability thatlight is scattered into the FOV. The present disclosure teaches anopposite solution for a cinema environment, wherein light is eitherabsorbed or re-directed in a deterministic fashion, to minimize thelocal ambient light level.

According to an embodiment of cinema eyewear, the interior surfaces ofthe temple region are designed to minimize scatter collected by the eye.Some techniques that are beneficial for accomplishing this are asfollows: 1) minimize the surface area of the frame (temple) interior; 2)use a surface finish that is substantially smooth to minimize randomscatter within the FOV; 3) use a material with high visible absorption;and 4) if possible, provide light control structures on surfaces, whichfurther re-direct light outside of the FOV.

FIG. 6 illustrates one embodiment of a frame 500 which may include a rimsection 502, lens 504 secured in the rim section 502, and a templeportion 506 connected to the rim section 502 via an attachment portion508. Large surface area parts, such as the temple and attachment point(or hinge) 506, 508 may be manufactured with light-control structuressuch as locally planar tilted surfaces 510 on the temple and/orattachment point 506, 508. Specular reflections from such structures,whether single or double, may occur in such a way that outgoing rays aredirected outside of the field of view. For instance, periodicstructures, similar to those used in LCD light control films (asmanufactured by e.g. 3M under the Vikuity trade name) can be designedsuch that incoming rays reflect from locally planar tilted surfaces. Aray incident from the screen is either directly reflected outside of theFOV or undergoes a secondary reflection from the structure beforeleaving the system. In either case, the structure angularly filters thelight incident on the surface in such a way that no light is steered tothe eye.

When designing eyewear for home use, the situation can be substantiallydifferent than in the cinema. Unless it is a home-theatre setup, whichis light controlled much like the cinema, stray light can be introducedfrom a number of illumination sources. However, the image source remainsan important contributor to stray light, and as such, many of the abovedesign principles continue to apply.

The situation is more complicated in (e.g.) a home 3D system situated ina living room. Here, there can be several background illuminationsources, incident from various angles. The frame design may incorporatelight shielding via panels that enclose the space between the lens andface in an attempt to block light introduced from extreme angles. To theextent that such panels are used, it is preferred that matte innersurfaces are not used. Rather, deterministic (e.g. periodic louvers)structures that angularly filter light introduced from both the screenand other ambient sources are desirable.

Additionally, anti-reflective (AR) coatings may desirably be used inhome use eyewear. In that case, simple specular surface for the sideshields would cause the face to be illuminated. Light scattering off ofthe face may then go back out through the lens (even by way of aspecular reflection off of the frame). In fact, because the face isilluminated much more brightly from the screen, it seems much moredifficult to engineer a baffled surface that prevents both thiscomponent the screen component from hitting the eye. Accordingly, asimple specular surface in combination with an AR may provide adesirable embodiment well suited to the home environment. FIG. 7illustrates an exemplary lens 600 having an AR coating and operable tobe incorporated into any embodiment disclosed herein. The lens 600includes a first anti-reflective coating 602 being disposed on anexterior surface of the lens 600, and a second anti-reflective coating604 being disposed on an interior surface of the lens 600.

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. Such an industry-accepted tolerance rangesfrom less than one percent to ten percent and corresponds to, but is notlimited to, component values, angles, et cetera. Such relativity betweenitems ranges between less than one percent to ten percent.

While various embodiments in accordance with the principles disclosedherein have been described above, it should be understood that they havebeen presented by way of example only, and not limitation. Thus, thebreadth and scope of the invention(s) should not be limited by any ofthe above-described exemplary embodiments, but should be defined only inaccordance with any claims and their equivalents issuing from thisdisclosure. Furthermore, the above advantages and features are providedin described embodiments, but shall not limit the application of suchissued claims to processes and structures accomplishing any or all ofthe above advantages.

Additionally, the section headings herein are provided for consistencywith the suggestions under 37 CFR 1.77 or otherwise to provideorganizational cues. These headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Specifically and by way of example, although the headings refer to a“Technical Field,” the claims should not be limited by the languagechosen under this heading to describe the so-called field. Further, adescription of a technology in the “Background” is not to be construedas an admission that certain technology is prior art to any invention(s)in this disclosure. Neither is the “Summary” to be considered as acharacterization of the invention(s) set forth in issued claims.Furthermore, any reference in this disclosure to “invention” in thesingular should not be used to argue that there is only a single pointof novelty in this disclosure. Multiple inventions may be set forthaccording to the limitations of the multiple claims issuing from thisdisclosure, and such claims accordingly define the invention(s), andtheir equivalents, that are protected thereby. In all instances, thescope of such claims shall be considered on their own merits in light ofthis disclosure, but should not be constrained by the headings set forthherein.

What is claimed is:
 1. Stereoscopic eyewear configured to reduce straylight, the eyewear comprising: a frame having rim sections; and lenses,comprising: a first lens operable to allow a first state of polarization(SOP) of light to pass through the first lens and operable to block asecond SOP of light from passing through the first lens and a secondlens operable to block the first SOP of light from passing through thesecond lens and operable to allow the second SOP of light to passthrough the second lens, further wherein the lenses are connected to therim sections of the frame, each lens comprising a field of view (FOV)having a half angle θ₀; wherein each rim section comprises an outerportion and an inner portion; and wherein a path is defined through amaximum height of the outer portion and a maximum height of the innerportion, the path being inclined at an angle α relative to alongitudinal axis defined by the lenses.
 2. The stereoscopic eyewear ofclaim 1, wherein the maximum height of the outer portion is greater thanthe maximum height of the inner portion.
 3. The stereoscopic eyewear ofclaim 2, wherein the outer portion comprises a sloped profile from anouter edge to an inner edge of the outer portion.
 4. The stereoscopiceyewear of claim 2, wherein the angle α is greater than a steepestincidence angle associated with a screen.
 5. The stereoscopic eyewear ofclaim 1, wherein the maximum height of the outer portion is less thanthe maximum height of the inner portion.
 6. The stereoscopic eyewear ofclaim 5, wherein the inner portion comprises a sloped profile from anouter edge to an inner edge of the inner portion.
 7. The stereoscopiceyewear of claim 5, wherein the angle α is greater than θ₀.
 8. Theeyewear of claim 1, wherein the frame comprises temple portions orattachment portions that comprise locally tilted surfaces operable toreflect incident light rays outside of the field of view of the lenses.9. The eyewear of claim 8, wherein the locally tilted surfaces aresubstantially smooth.
 10. The eyewear of claim 1, wherein the lenseseach comprise at least one anti-reflective coating.
 11. The eyewear ofclaim 10, wherein the lenses each comprise a plurality ofanti-reflective coatings, a first anti-reflective coating being disposedon an exterior surface of each lens, and a second anti-reflectivecoating being disposed on an interior surface of each lens.
 12. Thestereoscopic eyewear of claim 1, wherein the outer and inner portions ofeach rim section comprise an outer flange portion and an inner flangeportion, respectively, the outer and inner flange portions defining achannel therebetween, and wherein a portion of the each lens is disposedin the channel of a respective rim section.
 13. Stereoscopic eyewearconfigured to reduce stray light, the eyewear comprising: a frame havingrim sections; and lenses comprising: a first lens operable to allow afirst state of polarization (SOP) of light to pass through the firstlens and operable to block a second SOP of light from passing throughthe first lens and a second lens operable to block the first SOP oflight from passing through the second lens and operable to allow thesecond SOP of light to pass through the second lens, further wherein thelenses are connected to the rim sections of the frame, each lenscomprising a field of view (FOV) having a half angle θ₀; wherein eachrim section comprises an outer flange portion and an inner flangeportion, the outer and inner flange portions defining a channeltherebetween; wherein a portion of the each lens is disposed in thechannel of a respective rim section; wherein a path is defined through amaximum height of the outer flange portion and a maximum height of theinner flange portion, the path being inclined at an angle α relative toa longitudinal axis defined by the lenses; wherein the maximum height ofthe outer flange portion is greater than the maximum height of the innerflange portion and comprises a sloped profile from an outer edge to aninner edge of the outer flange; and wherein the angle α is greater thana steepest incidence angle associated with a screen.
 14. The eyewear ofclaim 13, wherein the frame comprises temple portions or attachmentportions that comprise locally tilted surfaces operable to reflectincident light rays outside of the field of view of the lenses.
 15. Theeyewear of claim 14, wherein the locally tilted surfaces aresubstantially smooth.
 16. The eyewear of claim 13, wherein the lenseseach comprise at least one anti-reflective coating.
 17. The eyewear ofclaim 16, wherein the lenses each comprise a plurality ofanti-reflective coatings, a first anti-reflective coating being disposedon an exterior surface of each lens, and a second anti-reflectivecoating being disposed on an interior surface of each lens.
 18. A methodof manufacturing stereoscopic eyewear configured to reduce stray light,the method comprising: forming a frame having rim sections; anddisposing lenses in the rim sections of the frame, each lens comprisinga field of view (FOV) having a half angle θ₀, wherein a first lens isoperable to allow a first state of polarization (SOP) of light to passthrough the first lens and operable to block a second SOP of light frompassing through the first lens and a second lens is operable to blockthe first SOP of light from passing through the second lens and operableto allow the second SOP of light to pass through the second lens,wherein each rim section comprises an outer portion and an innerportion; and wherein a path is defined through a maximum height of theouter portion and a maximum height of the inner portion, the path beinginclined at an angle α relative to a longitudinal axis defined by thelenses.
 19. The method of claim 18, wherein forming the frame comprisesforming locally tilted surfaces on temple portions or attachmentportions of the frame, the locally tilted surfaces operable to reflectincident light rays outside of the field of view of the lenses.
 20. Themethod of claim 18, further comprising disposing at least oneanti-reflective coating on the lenses.